Search

We describe the structural characterization of the capsular polysaccharides (CPSs) of Pasteurella multocida serotypes B and E. CPS was isolated following organic solvent precipitation of the supernatant from flask grown cells. Structural analysis utilizing nuclear magnetic resonance spectroscopy enabled the determination of the CPS structures and revealed significant structural similarities between the two serotypes, but also provided an explanation for the serological distinction. This observation was extended by the development of polyclonal sera to the glycoconjugate of serotype B CPS that corroborated the structural likenesses and differences. Finally, identification of these structures enabled a more comprehensive interrogation of the genetic loci and prediction of roles for some of the encoded proteins in repeat unit biosynthesis. [ABSTRACT FROM AUTHOR]

Dental caries remains a major health issue and the Gram-positive bacterium Streptococcus mutans is considered as the major pathogen causing caries. More recently, S. mutans has been recognised as a cause of endocarditis, ulcerative colitis and fatty acid liver disease along with the likelihood of increased cerebral hemorrhage following a stroke if S. mutans is present systemically. We initiated this study to examine the vaccine candidacy of the serotype specific polysaccharides elaborated by S. mutans. We have confirmed the carbohydrate structures for the serotype specific rhamnan containing polysaccharides from serotypes c, f and k. We have prepared glycoconjugate vaccines using the rhamnan containing polymers from serotypes f and k and immunised mice and rabbits. We consistently obtained a robust immune response to the glycoconjugates with cross-reactivity consistent with the structural similarities of the polymers from the different serotypes. We developed an opsonophagocytic assay which illustrated the ability of the post-immune sera to facilitate opsonophagocytic killing of the homologous and heterologous serotypes at titers consistent with the structural homologies. We conclude that glycoconjugates of the rhamnan polymers of S. mutans are a potential vaccine candidate to target dental caries and other sequelae following the escape of S. mutans from the oral cavity. [ABSTRACT FROM AUTHOR]